Field of the Invention
The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire having sipes which may minimize a movement of a tire tread block due to a stress generated during contacting with a ground, improve soil drainage, and increase a traction force in the latter half of use.
Description of the Related Art
As is generally known, a tread surface of a tire of an automobile, which contacts with a ground, includes grooves formed therein, and tread blocks which are defined by the grooves and formed thereon while having a constant tread pattern.
In order to improve a traction force and a braking force, the sipes are formed in the tread block. The sipe serves to appropriately adjust a stiffness of the tread block so as to satisfy a performance required for the tire.
In particular, the sipe applied to a pneumatic tire for a heavy load used in a truck or a bus is formed in a shape that can effectively prevent a stress concentration in accordance with the high load.
The sipes applied to the conventional tread block are formed in a vertical direction with respect to the tread, such that it is possible to disperse a stress only in a traverse direction with respect to a driving direction. However, when applying the sipes to the tread block for dispersing the stress, an entire stiffness of the tread block is decreased, thereby causing a problem such as abnormal abrasion.
In addition, as a cross-sectional shape of the sipe is complicated, the stiffness of the tread block is increased, but it is difficult to manufacture the tire. Further, the sipe has a structure that, when soil enters into the sipe, it is difficult to discharge the soil, thus the introduced soil is accumulated in the sipe, and the sipe is clogged. When becoming the tire in the latter half of use, a depth of the sipe of the tread block is decreased, such that there is a problem of reducing the traction force.